Molecular mechanisms of Staphylococcus aureus nasopharyngeal colonization.

Staphylococcus aureus is responsible for a wide range of different infections ranging in severity from mild to fatal. However, it primarily exists as a commensal organism in a number of different anatomical sites including the nasopharynx. Although colonization itself is a harmless state, colonized individuals are at risk of endogenous infection when S. aureus enters otherwise sterile sites via wounds or indwelling medical devices. As such, studies of colonization may identify important targets for vaccines or other prophylactic approaches. Colonization is a dynamic process; S. aureus must attach to host surfaces, overcome immune components and compete with other commensal microbes. This occurs via a number of surface-attached and secreted proteins and other factors such as wall teichoic acid. In addition, colonizing S. aureus must constantly replicate to maintain its niche and exclude other strains. These myriad interactions provide a strong selective pressure for the maintenance or enhancement of mechanisms of adhesion, invasion and immune evasion. The evolutionary implications of this may explain why S. aureus is such a capable pathogen because many of the proteins involved in colonization have also been identified as virulence factors. This review describes the diverse molecular mechanisms used by S. aureus to colonize the host and discusses how the pressures that have selected for these may have led to its virulence.

Methyl palmitate, an acaricidal compound occurring in green walnut husks.

Walnut, Juglans regia L., is known for its insecticidal activities to a range of herbivores and microbes. Isolation and identification of bioactive compounds from walnut is a potential approach for the development of new pesticides. Laboratory experiments were carried out to investigate the acaricidal activities of green husk extracts of walnut. Bioassay-guided fractionation of petroleum-ether extracts of walnut led to the identification of a common plant-borne fatty acid ester, methyl palmitate (MP), which produced strong acaricidal activity (62.8% mortality) at 1 mg/ml at 24 h. The structure of MP was characterized with infrared spectrum and NMR, and the identification of MP confirmed using an authentic standard on high-performance liquid chromatography. Based on a slide dip bioassay, 10 mg/ml MP provided 97.9% mortality against adults of Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae), whereas mortality against eggs was much lower (57.2%).

Acaricidal activity of Juglans regia leaf extracts on Tetranychus viennensis and Tetranychus cinnabarinus (Acari: Tetranychidae).

Leaf extracts of the walnut, Juglans regia L., were evaluated under laboratory conditions to determine their acaricidal activity on the mites Tetranychus cinnabarinus (Boisduval) and Tetranychus viennensis Zacher (Acari: Tetranychidae). Extracts had both contact and systemic toxicity to these mites. The four solvents tested for preparing crude extracts were petroleum ether, chloroform, ethyl acetate, and methanol. Methanol was the most efficient solvent, with an extraction rate from 17.06 + 0.80 to 20.27 +/- 0.28%. Petroleum ether was the least effective solvent, with extraction rates from 2.30 +/- 0.13 to 2.71 +/- 0.13%. However, the crude extracts with petroleum ether resulted in the highest mite mortality (79.04 +/- 0.52%) in a slide dip bioassay. Mites mortalities from the concentrated extracts prepared by chloroform, ethyl acetate, methanol, or distilled water were significantly lower than petroleum ether. The mean lethal concentrations (LC50) of the extracts from petroleum ether, chloroform, ethyl acetate, methanol, and distilled water to the two mite species were 0.73 +/- 0.04, 1.66 +/- 0.28, 4.96 +/- 0.35, 7.45 +/- 0.67, and 9.91 +/- 0.32 mg/ml, respectively. After liquid chromatography and thin-layer chromatography, the concentrated extracts of petroleum ether were separated into eight fractions and tested for acaricidal activity. Fraction 6 produced significantly higher mite mortality rates than the other groups, killing approximately 90% of both species.

Acaricidal activities of extracts of Kochia scoparia against Tetranychus urticae, Tetranychus cinnabarinus, and Tetranychus viennensis (Acari: Tetranychidae).

Extracts of an annual herbaceous plant, Kochia scoparia (L.) Schrad (Macrophomina), were bioassayed to determine their acaricidal activities against Tetranychus urticae Koch, Tetranychus cinnabarinus (Boisduval), and Tetranychus viennensis Zacher (Acari: Tetranychidae) in the laboratory. Extracts had both contact and systemic toxicity to these mites. Three solvents were tested for preparing crude extracts: petroleum ether, chloroform, and methanol. Methanol was the most effective solvent, extracting 3.11-4.53% of the acaricide. Petroleum ether was the least effective solvent, extracting 1.25-1.54%. However, extracts with chloroform resulted in the highest mite mortality (78.86%), and ultrasound-assisted extraction required the least time (10 min). Concentrated extracts were prepared using chloroform, methyl acetate, or distilled water as a solvent. Mite mortalities from the concentrated extracts by methyl acetate or distilled water were significantly lower than those by chloroform. The mean lethal concentrations (LC50) of the extracts by chloroform, methyl acetate, and distilled water to the mites were 0.71 +/- 0.06, 2.08 +/- 0.16 and 8.75 +/- 0.062 mg/ml, respectively. After liquid chromatography and thin layer chromatography, the concentrated extracts by chloroform were separated into seven groups of isolated fractions and tested for acaricidal activity.

Factors contributing to the amount of vehicular damage resulting from collisions between four-wheel drive vehicles and passenger cars.

This study examines the vehicular damage resulting from motor vehicle crashes involving four-wheel drive vehicles and passenger cars in the state of Oklahoma. In particular, the focus of the analysis is on differences in vehicular damage to passenger cars and four-wheel drive vehicles. Results indicate that passenger cars sustain significantly greater vehicular damage than four-wheel drive vehicles. In addition, several other factors significantly influence the level of damage resulting from collisions between four-wheel drive vehicles and passenger cars. Driver behavior or unsafe acts, represented by the rate of travel prior to the collision, failure to yield, failure to obey a stoplight or a stop sign, the consumption of alcohol and the use of drugs, also contributed to the amount of vehicular damage. In addition, results also indicate that the level of damage was influenced significantly by environmental factors, represented by a reduced intensity of light, wet or slippery roadways and the type of collision. The findings reinforce the importance of a number of policy initiatives that may reduce the vehicular damage resulting from collisions involving four-wheel drive vehicles and passenger cars. For example, the study indicates a need to initiate legislation that lowers the speed limit during dark and twilight hours, commits additional resources to road maintenance to reduce unsafe road conditions, and stimulates improvements in automotive design that provide better lateral protection to vehicles.

(Z)-3-hexenyl (R)-3-hydroxybutanoate: a male specific compound in three North American decorator wasps Eucerceris rubripes, E. conata and E. tricolor.

The males of the decorator wasps Eucerceris have been observed to display abdomen-dragging behavior on plants surrounding their nest. It is thought that this applies a territorial-marking sex pheromone that serves to alert females to the males' territory for courtship and mating. The extracts of three species E. rubripes, E. conata, and E. tricolor have been analyzed by GC-MS. The gas chromatograms revealed the presence, in large quantities, of one common volatile compound in the male head extracts. By analogy with the closely related bee wolves Philanthus, we believe the pheromone is produced in the mandibular glands. Utilizing mass spectrometry, microreactions, FT-IR, and 1H and 13C NMR spectroscopy the structure of the pheromone was proposed to be (Z)-3-hexenyl 3-hydroxybutanoate, which was confirmed by synthesis. The absolute configuration of the chiral center was determined to be R for the three species by preparing the Mosher esters of the insect samples and comparing their GC retention times with a synthetic sample of known absolute configuration. In addition 2- and 3-hexenoic acid and some aromatic compounds were also found in varying quantities in both males and females along with hydrocarbons and fatty acids, although no species-specific profiles emerged.

Studies of the operator region of the Staphylococcus aureus beta-lactamase operon.

The repressor proteins BlaI and MecI bind similarly to the bla operator implicated in the regulation of beta-lactamase synthesis in Staphylococcus aureus. BlaI binds to two separate dyads but neither copper-phenanthroline footprinting nor dimethyl sulphate (DMS) methylation protection assays produced any evidence of a change in the geometry of the DNA between the two dyads. It is concluded that BlaI molecules bound at the dyads probably do not cause bending or looping of the intervening DNA. DMS protection assays of BlaI binding to the bla operator in vitro and in vivo gave similar results so that it is tentatively concluded that the in vitro results are an accurate reflection of the in vivo situation. Deletion of the dyad nearest to the blaZ gene resulted in decreased synthesis of the chloramphenicol acetyltransferase reporter protein synthesized from the blaZ promoter/translation initiator. Explanations for this are considered.

An analysis of factors associated with seat belt use: prevention opportunities for the medical community.

Motor vehicle collisions are a significant cause of morbidity and mortality in the Oklahoma population. The cost associated with this morbidity and mortality is exacerbated by the failure of individuals to use seat belts. Numerous organizations believe that seat belt compliance can be improved through physician counseling. This would allow medical resources to be redirected towards other health problems. Analysis was performed using the Oklahoma Department of Public Safety (ODPS) crash file and the hospital in-patient data discharge file from the Oklahoma State Department of Health (OSDH). These provide a profile of Oklahoma drivers who do not use seat belts. This analysis allows physicians to pinpoint and advise those individuals most likely to not utilize seat belts about the benefits of seat belt use. The results of the analysis show that non-seat belt-users tend to be young and male. Significant predictors of seat belt use are age, gender, alcohol use, time of day (day versus night), driver location (urban versus rural), vehicle type (pick up versus passenger car), and decreased hospital charges. These results show that increased seat belt use can lead to significant decreases in fatalities related to motor vehicle crashes and a decline in associated hospital charges for those who survive. Physicians should encourage seat belt use by their patients and inform them of the risks associated with failure to use seat belts.

Survival and homeostatic proliferation of naive peripheral CD4+ T cells in the absence of self peptide:MHC complexes.

TCR-self peptide:MHC interactions play a critical role in thymic positive selection, yet relatively little is known of their function in the periphery. It has been suggested that continued contact with selecting MHC molecules is necessary for long-term peripheral maintenance of naive T cells. More recent studies have also demonstrated a role for specific self peptide:MHC complexes in the homeostatic expansion of naive T cells in lymphopenic mice. Our examination of these processes revealed that, whereas self class II MHC molecules do have a modest effect on long-term survival of individual CD4+ T cells, interactions with specific TCR ligands are not required for peripheral naive CD4+ T cell maintenance. In contrast, selective engagement of TCRs by self-peptide:MHC complexes does promote proliferation of CD4+ T cells under severe lymphopenic conditions, and this division is associated with an activation marker phenotype that is different from that induced by antigenic stimulation. Importantly, however, the ability of naive T cells to divide in response to homeostatic stimuli does not appear to be stringently dependent on TCR-self peptide:MHC interactions. Therefore, these results show that the factors regulating survival and homeostatic expansion of naive T cells in the periphery are not identical. In addition, we provide evidence for a novel form of T cell proliferation that can occur independently of TCR signaling and suggest that this reflects another mechanism regulating homeostatic T cell expansion.

The critical role of CD40/CD40L in the CD4-dependent generation of CD8+ T cell immunity.

Control of virus infections and eradication of tumors usually involves the lytic activity of CD8+ cytotoxic T lymphocytes (CTLs). The induction of effective CTL immunity relies on several factors, one of the most important of which is CD4+ T cell help. Numerous studies have demonstrated the dependence of CTL priming on the presence of CD4+ T cells, but until recently little was known of the mechanisms regulating this process. Based on reports that CD4+ and CD8+ T cells must recognize antigen on the same antigen-presenting cell (APC), help was originally thought to be provided through the delivery of short-range, CD4+ T cell-secreted cytokines. However, the results of subsequent studies favor an alternative mechanism, whereby CD4+ T cells modify the APC, converting it into a stimulatory cell for CD8+ T cell priming. It is important that CD40 and its ligand, CD40L, have been implicated in the provision of this help and, in particular, the generation of long-lasting CTL memory.

Characterization of the ovalbumin-specific TCR transgenic line OT-I: MHC elements for positive and negative selection.

The present report provides the first extensive characterization of the OT-I TCR transgenic line, which produces MHC class I-restricted, ovalbumin-specific, CD8+ T cells (OT-I cells). These cells are shown to be positively selected in vivo in H-2b C57BL/6 mice and in bm5 mice, which express the Kbm5 mutant molecule. In contrast, OT-I cells were not selected by mutant Kb molecules in bm1, bm3, bm8, bm10, bm11 or bm23 mice. Interestingly, however, when positive selection was examined in vitro in foetal thymic organ culture (FTOC), bm1 and bm8 were still poorly selective, but the bm3 haplotype now selected as efficiently as B6. The ability to select in vitro correlated with the capacity to present the ovalbumin (OVA) peptide to OT-I cells, as measured by induction of an OVA-specific proliferative response. These results suggest that a lower affinity TCR:MHC interaction may be necessary for positive selection in FTOC compared with selection in situ.

Elective surgery and the HIV-positive patient: medical, legal, and ethical issues.

The ethical and legal issues surrounding the healthcare provider's obligation to provide care for patients have been a topic of debate since the beginning of modern medicine. The human immunodeficiency virus (HIV)-positive patient requesting cosmetic or elective surgery provides yet another situation in which the physician's ethical and legal responsibilities for the patient become a topic of debate. The risks involved to the physician and patient are first discussed, and then current ethical theory and legal decisions are reviewed. Finally, some conclusions are attempted from the varied opinions in the literature surrounding this controversial topic.

Impaired invariant chain degradation and antigen presentation and diminished collagen-induced arthritis in cathepsin S null mice.

Cathepsins have been implicated in the degradation of proteins destined for the MHC class II processing pathway and in the proteolytic removal of invariant chain (Ii), a critical regulator of MHC class II function. Mice lacking the lysosomal cysteine proteinase cathepsin S (catS) demonstrated a profound inhibition of Ii degradation in professional APC in vivo. A marked variation in the generation of MHC class II-bound Ii fragments and presentation of exogenous proteins was observed between B cells, dendritic cells, and macrophages lacking catS. CatS-deficient mice showed diminished susceptibility to collagen-induced arthritis, suggesting a potential therapeutic target for regulation of immune responsiveness.

Chemical analysis of the swarming trail pheromone of the social wasp Polybia sericea (Hymenoptera: Vespidae).

The behaviour of those polistine wasps which found their nests by swarming, suggests that these species use trail pheromones for leading the swarm to the location chosen for the new nest. Apart from a recent report regarding the ropalidine Polybioides tabidus, where the pheromone is thought to originate from the Dufour gland, nothing is known about the chemistry of such pheromones. Polybia sericea is the only species for which the source of the trail pheromone, the Richards' gland, is known with certainty. The chemistry of the Richards' gland secretion of this species has been investigated in the present work and shown to be a complex mixture where the major compounds are alkyl and aromatic aldehydes, fatty acids, 3-phenylpropanoic acid, ketones, a macrolactone, a pyranone compound and nerolidol.

Tumors of the parapharyngeal space.

The parapharyngeal space may give rise to a wide variety of neoplasms. The goal of this article is to present a simple algorithm for the recognition and evaluation of parapharyngeal space lesions by primary care physicians so that timely referral can be made to an otolaryngologist for definitive therapy.

Allergic fungal sinusitis.

Allergic fungal sinusitis (AFS) is a recently described entity that has been frequently misdiagnosed in the past. AFS is now felt to be the most common cause of fungal sinusitis. There is now a sufficient experience to make the diagnosis and the causative organisms have been elucidated. However, controversy continues to surround the pathophysiology and treatment of this challenging disease.

A potential signaling role for profilin in pollen of Papaver rhoeas.

Regulation of pollen tube growth is known to involve alterations in intracellular calcium levels and phosphoinositide signaling, although the mechanisms involved are unclear. However, it appears likely that pollination events involve a complex interplay between signaling pathways and components of the actin cytoskeleton in pollen. In many eukaryotic cells, actin binding proteins function as stimulus-response modulators, translating signals into alterations in the cytoplasmic architecture. In this study, we examined whether profilin, which is a member of this class of signaling intermediate, might play a similar role in pollen. We have analyzed the functional properties of native profilin from pollen of Papaver rhoeas and have investigated the effects of profilin on the phosphorylation of pollen proteins in vitro by adding a slight excess of profilin to cytosolic pollen extracts. We present clear evidence that profilin interacts with soluble pollen components, resulting in dramatic alterations in the phosphorylation of several proteins. We also show, albeit in vitro, the involvement of profilin in modulating the activity of a signaling component(s) affecting protein phosphorylation. Our data, which suggest that pollen profilin can regulate actin-based cytoskeletal protein assembly and protein kinase or phosphatase activity, indicate a possible role for the involvement of profilin in signaling pathways that may regulate pollen tube growth.

Schneiderian papilloma.

Schneiderian papillomas are benign neoplasms that are associated with three key characteristics: tendency to recur, capacity for local destruction, and association with squamous cell carcinoma. They are classified into inverting, fungiform, and oncocytic varieties. The inverting and fungiform varieties are the most common, and the inverting variety has the highest rate of association with malignancy. The inverting and oncocytic varieties are classically found on the lateral nasal wall with extension into the adjacent sinuses. The fungiform lesion is typically found on the nasal septum. Treatment of these lesions is primarily surgical, with rather aggressive surgery mandated in most cases. There may be a limited role for radiation therapy and close follow-up of these patients is mandatory. These neoplasms arise from a unique area of the respiratory epithelium, termed the schneiderian mucosa. Although these are relatively rare lesions, their association with carcinoma and their tendency to be confused with more common lesions make this topic important for all practitioners.

Reactive astrocytes express the embryonic intermediate neurofilament nestin.

Nestin is a neurofilament protein expressed by the immediate precursors to neurons and glia in rats and humans. Nestin immunoreactivity in the rat CNS was studied following kainic acid (KA) hippocampal lesions. Numerous nestin positive cells within the KA lesion were confirmed to be reactive astrocytes by their immunoreactivity for glial fibrillary acidic protein (GFAP). The number of these cells decreased with time after the KA lesion and no astrocyte immunostaining for nestin was observed in control animals. A subset of nestin-positive cells in the ventricular subependymal region appeared to be radial glial cells, extending to cell body layers. Nestin is one of several embryonic markers expressed by reactive astrocytes, suggesting an embryonic reversion induced by the KA lesion, possibly to enhance functional recovery.